Background: Myelodysplastic syndromes (MDS) are heterogeneous in outcomes and associated with high frequencies of cytogenetic abnormalities. The chromosomal abnormalities, −5/5q, −7/7q, +8, and del(20q), are the most commonly tested regions in MDS by fluorescent in-situ hybridization (FISH). The objective of this study is to determine MDS associated chromosomal abnormalities that would be detectable if only conventional chromosomal (CC) analysis was performed without the FISH panel.Design: One hundred thirty bone marrow consecutive samples, 64 female and 66 male patients, which were sent to our cytogenetic laboratory with the initial presumptive diagnosis of MDS, are selected for this study. All cases were evaluated simultaneously by CC as well as MDS FISH panel.Results: CC analysis detected clonal chromosomal abnormalities in 42 cases (32.3%) while FISH testing on the same specimens identified all 31 cases (23.8%) containing the MDS associated abnormalities 5/5q, −7/7q, +8 and/or del(20q). Moreover, CC detected additional chromosomal abnormalities including rings, deletions, translocations, inversions, and markers in 16 of the 31 (51%) FISH positive cases, and identified 11 (11.1 %) cases with other chromosomal abnormalities among the 99 FISH negative cases.Conclusions: CC analysis has the ability to detect all MDS associated abnormalities as well as other chromosomal abnormalities that are undetectable by the locus-specific probes of MDS FISH panel. In MDS, combining FISH and CC analyses does not appear to increase the detection rate of genetic aberrations.Category: Hematopathology